Golf ball

Abstract

An object of the present is to provide a golf ball having a high spin rate on approach shots under the wet condition and rough condition. The present invention provides a golf ball comprising a golf ball body, and a paint film formed on a surface of the golf ball body, wherein the paint film has a martens hardness of 2.0 mgf/μm 2 or less, and a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 1.6 or more.

The invention claimed is:  
     
       1. A golf ball comprising
 a golf ball body, and 
 a paint film formed on a surface of the golf ball body, 
 wherein the paint film has a martens hardness of 2.0 mgf/μm 2  or less, has a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 1.6 or more, and contains a filler in a content ranging from 10 mass % to 50 mass % and wherein a base resin constituting the paint film is polyurethane obtained by a reaction between a polyol component and a polyisocyanate component, and the polyisocyanate component includes a biuret-modified product of hexamethylene diisocyanate. 
 
     
     
       2. The golf ball according to  claim 1 , wherein the paint film has a 10% modulus of 100 kgf/cm 2  or less. 
     
     
       3. The golf ball according to  claim 1 , wherein the paint film has a 10% modulus of 50 kgf/cm 2  or less. 
     
     
       4. The golf ball according to  claim 1 , wherein the paint film has a 50% modulus of 30 kgf/cm 2  or more. 
     
     
       5. The golf ball according to  claim 1 , wherein the filler includes at least one filler selected from the group consisting of titanium oxide, barium sulfate, talc, calcium carbonate, clay, and white carbon. 
     
     
       6. The golf ball according to  claim 1 , wherein the golf ball has a cover with a Shore D hardness of 61 or less. 
     
     
       7. The golf ball according to  claim 6 , wherein the cover has a thickness ranging from 0.3 mm to 1.0 mm. 
     
     
       8. The golf ball according to  claim 1 , the paint film has a thickness ranging from 5 μm to 40 μm. 
     
     
       9. The golf ball according to  claim 3 , wherein the paint film has a 10% modulus of 5 kgf/cm 2  or more. 
     
     
       10. The golf ball according to  claim 4 , wherein the paint film has a 50% modulus of 200 kgf/cm 2  or less. 
     
     
       11. The golf ball according to  claim 1 , wherein the paint film has a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 15 or less. 
     
     
       12. The golf ball according to  claim 1 , wherein the polyol component has a hydroxyl value ranging from 10 mgKOH/g to 400 mgKOH/g. 
     
     
       13. The golf ball according to  claim 1 , wherein the polyisocyanate component contains a mixture of the biuret-modified product of hexamethylene diisocyanate and an isocyanurate of isophorone diisocyanate. 
     
     
       14. The golf ball according to  claim 13 , wherein a blending ratio of the biuret-modified product of hexamethylene diisocyanate and the isocyanurate of isophorone diisocyanate is such that the biuret-modified product of hexamethylene diisocyanate : the isocyanurate of isophorone diisocyanate is 1:0 to 0.7:0.3. 
     
     
       15. The golf ball according to  claim 1 , wherein the polyisocyanate component has an isocyanate content (NCO %) ranging from 0.5 mass % to 45 mass %. 
     
     
       16. The golf ball according to  claim 1 , wherein a molar ratio (NCO/OH) of the isocyanate group (NCO) of the polyisocyanate component to the hydroxyl group (OH) of the polyol component ranges from 1.0 to 1.4 in the reaction. 
     
     
       17. A golf ball comprising
 a colored golf ball body, and 
 a paint film formed on a surface of the golf ball body, 
 wherein the paint film has a martens hardness of 2.0 mgf/μm 2  or less, a 10% modulus ranging from 5 kgf/cm 2  to 100 kgf/cm 2 , a 50% modulus ranging from 30 kgf/cm 2  to 200 kgf/cm 2  and a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 1.6 or more, and 
 wherein the paint film is a substantially transparent film containing a filler in a content ranging from 10 mass % to 50 mass % and wherein a base resin constituting the paint film is polyurethane obtained by a reaction between a polyol component having a weight average molecular weight ranging from 500 to 150,000 and a polyisocyanate component, and the polyisocyanate component includes a biuret-modified product of hexamethylene diisocyanate. 
 
     
     
       18. The golf ball according to  claim 17 , wherein the paint film has a thickness ranging from 5 μm to 40 μm. 
     
     
       19. The golf ball according to  claim 1 , wherein the golf ball has a cover with a Shore D hardness of 45 or less. 
     
     
       20. The golf ball according to  claim 1 , wherein the polyol component has a weight average molecular weight ranging from 500 to 150,000. 
     
     
       21. The golf ball according to  claim 20 , wherein the polyisocyanate component contains a mixture of a biuret-modified product of hexamethylene diisocyanate and an isocyanurate of isophorone diisocyanate having a blending ratio such that biuret-modified product of hexamethylene diisocyanate: isocyanurate of isophorone diisocyanate is in the range of 1:0 to 0.7:0.3. 
     
     
       22. A golf ball comprising
 a golf ball body, and 
 a paint film formed on a surface of the golf ball body, 
 wherein the paint film has a martens hardness of 2.0 mgf/μm 2  or less, has a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 1.6 or more, and contains a filler in a content ranging from 10 mass % to 50 mass %; 
 wherein a base resin constituting the paint film is polyurethane obtained by a reaction between a polyol component and a polyisocyanate component, and the polyisocyanate component includes a biuret-modified product of hexamethylene diisocyanate; 
 wherein the filler includes at least one filler selected from the group consisting of titanium oxide, barium sulfate, talc, calcium carbonate, clay, and white carbon; 
 wherein the golf ball has a cover with a Shore D hardness of 61 or less; 
 wherein the cover has a thickness ranging from 0.3 mm to 1.0 mm; 
 wherein the polyisocyanate component contains a mixture of the biuret-modified product of hexamethylene diisocyanate and an isocyanurate of isophorone diisocyanate; and 
 wherein a blending ratio of the biuret-modified product of hexamethylene diisocyanate and the isocyanurate of isophorone diisocyanate is such that the biuret-modified product of hexamethylene diisocyanate: the isocyanurate of isophorone diisocyanate is 1:0 to 0.7:0.3.